1. Field of the Invention
The present invention relates to a technique for manufacturing an electron source and an image-forming apparatus to which the electron source is applied, and more particularly to an apparatus and a method for manufacturing an electron source having a plurality of electron-emitting devices.
2. Related Background Art
Conventionally, two types of electron-emitting device, i.e., a hot cathode device and a cold cathode device are known. As one of these devices, i.e., the cold cathode device, for example, a field emission device (which will be referred to as an FE hereinafter), a metal/insulation layer/metal emission device (which will be referred to as an MIM hereinafter) or a surface conduction emission device are known.
As an example of the FE, there is known a device disclosed in W. P. Dyke and W. W. Dolan, xe2x80x9cField emissionxe2x80x9d, Advance in Electron Physics, 8, 89 (1956) or that disclosed in C. A. Spindt, xe2x80x9cPhysical properties of thin-film field emission cathodes with molybdenium conesxe2x80x9d, J. Appl. Phys., 47, 5248 (1976).
Further, as an example of the MIM, C. A. Mead, xe2x80x9cOperation of tunnel-emission Devicesxe2x80x9d, J. Appl. Phys., 32, 646 (1961) is known.
Furthermore, as the surface conduction emission device, an example of M. I. Elinson Radio Eng. Electron Phys., 10, 1290, (1965) or later-described another example is known.
The surface conduction emission device utilizes such a phenomenon as that flowing an electric current through a small-sized thin film formed on a substrate in parallel to a film surface causes electron emission to be produced. As the surface conduction emission device, there are reported a device using an Au thin film [G. Dittmer: xe2x80x9cThin Solid Filmsxe2x80x9d, 9,317 (1972)], a device using an In2O3/SnO2 thin film [M. Hartwell and C. G. Fonstad:xe2x80x9cIEEE Trans. ED Conf.xe2x80x9d, 519 (1975)], a device using a carbon thin film [Hisashi Araki and et al.: Vacuum, Vol. 26, No. 1, 22 (1983)] and others, as well as the above-described device using an SnO2 thin film by Elinson and the like.
As a typical example of the device structure of these surface conduction emission devices, a plan view of the above-mentioned device by M. Hartwell and et al. is shown in FIG. 22. In the drawing, reference numeral 3001 denotes a substrate, and 3004 designates an electroconductive thin film consisting of a metal oxide formed by spattering. The electroconductive thin film 3004 is formed into a planar H-like shape as shown in the drawing. When a later-described energization operation called an energization forming operation is performed with respect to the electroconductive thin film 3004, an electron-emitting region 3005 is formed. In the drawing, a distance L is set to 0.5 to 1 [mm] and W is set to 0.1 [mm]. Although the electron-emitting region 3005 having a rectangular shape is shown in the central part of the electroconductive thin film 3004 for the sake of convenience, this is a typical arrangement and does not faithfully represent a position or a shape of the actual electron-emitting region.
In the above-described surface conduction emission device including the devices by M. Hartwell and others, it is general to form the electron-emitting region 3005 by carrying out the energization operation called the energization forming to the electroconductive thin film 3004 before performing the electron emission. That is, the energization forming means that a constant direct-current voltage or a direct-current voltage which rises at a very slow rate of, e.g., approximately 1V/min is applied to both ends of the electroconductive thin film 3004 for energization and the electroconductive thin film 3004 is then locally fractured, deformed or transformed to form the electron-emitting region 3005 having an electrically high resistance. It is to be noted that a fissure is generated to a part of the electroconductive thin film 3004 which has been locally fractured, deformed or transformed. When an appropriate voltage is applied to the electroconductive thin film 3004 after the energization forming, the electron emission is performed in the vicinity of the fissure.
Since the surface conduction emission device has a simple structure and can be easily manufactured, a plurality of devices can be advantageously formed over a large area. Therefore, as disclosed in, e.g., Japanese Patent Application Laid-open No. 64-31332 by the present applicant, a method for arranging and driving a plurality of devices has been studied.
As an application of the surface conduction emission device, for example, an image-forming apparatus such as an image-displaying apparatus or an image-recording apparatus or a charged beam source and the like have been studied.
In particular, as an application to the image-displaying apparatus, an image-displaying apparatus using a combination of the surface conduction emission device and a phosphor which emits light by irradiation of an electron beam has been studied as disclosed in, e.g., U.S. Pat. No. 5,066,883 or Japanese Patent Application Laid-open No. 2-257551 by the present applicant. An image-displaying apparatus using a combination of the surface conduction emission device and the phosphor is expected for its characteristic superior to a prior art image-displaying apparatus adopting any other mode. For example, it can be said that such an apparatus is superior to a recently spread liquid crystal display unit in that this apparatus is of a spontaneous light emission type which requires no back light and has a wider view angle.
The present applicants have tried production of the surface conduction emission device having various materials and structures by a variety of methods in addition to the devices described in the above prior arts. Further, they have studied a multi-electron source in which plural surface conduction emission devices are arranged and an image-displaying apparatus to which the multi-electron source is applied.
The present applicants have tried manufacturing of the multi-electron beam source obtained by an electrical wiring method such as shown in FIG. 23. That is the multi-electron beams source in which a plurality of surface conduction emission devices are arranged in the two-dimensional manner and these devices are wired in the matrix form.
In the drawing, reference numeral 4001 denotes a typically shown surface conduction emission device; 4002, a row-directional wiring; and 4003, a column-directional wiring. Although the row-directional wiring 4002 and the column-directional wiring 4003 actually have the finite electric resistance, the wiring resistance 4004 and 4005 is shown in the drawing. The above-described wiring method is referred to as a simple matrix wiring.
Incidentally, although a 6xc3x976 matrix is shown for the sake of convenience, the scale of the matrix is not restricted thereto, and the devices whose number can suffice the desired image display are arranged and wired in case of, for example, the multi-electron beam source for the image-displaying apparatus.
In the multi-electron beam source in which the surface conduction emission devices are simple-matrix-wired, an appropriate electric signal is applied to the row-directional wiring 4002 and the column-directional wiring 4003 in order to output a desired electron beam. For example, in order to drive the surface conduction emission device in an arbitrary row in the matrix, a selected voltage Vs is applied to the row-directional wiring 4002 for a selected row and a non-selected voltage Vns is applied to the row-directional wiring 4002 for a non-selected row at the same time. In synchronism with this, a drive voltage Ve for outputting an electron beam is applied to the column-directional wiring 4003. According to this method, if a drop in voltage due to the wiring resistance 4004 and 4005 is ignored, a voltage of Vexe2x88x92Vs is applied to the surface conduction emission device in the selected row and a voltage Vexe2x88x92Vns is applied to the surface conduction emission device in the non-selected row. If Ve, Vs and Vns are set to voltages having appropriate values, an electron beam having a desired intensity must be outputted from only the surface conduction emission device in the selected row. Further, if different voltages Ve are applied to each of the column-directional wiring, an electron beam having a different intensity must be outputted from each device in the selected row. Since the response speed of the surface conduction emission device high, changing a duration of time for applying the drive voltage Ve must change a duration of time for outputting the electron beam.
Therefore, various applications of the multi-electron beam source in which the surface conduction electron devices are wired in the simple matrix form are considered, and the multi-electron beam source is expected to be applied as the electron source for the image-displaying apparatus when a voltage signal responsive to, e.g., image information is appropriately applied.
On the other hand, as a result of the eager study for improving the characteristic of the surface conduction electron-emitting device, the present inventors have discovered that execution of the energization activation operation in the manufacturing process is effective.
As described above, when forming the electron-emitting region of the surface conduction electron-emitting device, there is performed an operation (energization forming operation) for flowing an electric current through the electroconductive thin film to locally fracture, deform or transform the thin film, thereby forming a fissure. The electron-emitting characteristic can be greatly improved by further performing the energization activation operation.
That is, the energization activation operation means an operation by which energization is applied to the electron-emitting region formed by the energization forming operation under an appropriate condition and carbon or carbon compound is deposited in the vicinity of this region. For example, in the vacuum atmosphere having a full pressure of 10xe2x88x924 to 10xe2x88x925 [Torr] in which an organic matter having an appropriate partial pressure exists, periodic application of a voltage pulse causes any of monocrystal graphite, polycrystal graphite and amorphous carbon or a mixture thereof to be deposited in the vicinity of the electron-emitting region so as to have a film thickness of not more than 500 [xc3x85]. However, this condition is just an example, and it is needless to say that such a condition should be appropriately modified in accordance with a material or a shape of the surface conduction emission device.
When such an operation is conducted, the emission current can be typically centuplicated with the same applied voltage as compared with that obtained immediately after the energization forming. It is to be noted that reduction in the partial pressure of the organic matter in the vacuum atmosphere is desirable after completion of the energization activation operation.
Therefore, even in production of the above-described multi-electron source in which a plurality of the surface conduction electron-emitting devices are wired in the form of a simple matrix, application of the energization activation operation to each device is desirable.
When applying the surface conduction electron-emitting device, the manufacturing process of which includes the high resistance operation and the energization activation operation, to the image-forming apparatus in this manner, there occur the following problems. The problems of the energization activation operation in the manufacturing process will be described hereunder.
In various kinds of image-forming panels to which the surface conduction electron-emitting device is applied, an image with high grade and high definition is understandably desired. To realize this, for example, a plurality of surface conduction electron-emitting devices wires in the form of a simple matrix are used. Thus the arrangement of vast many devices in which numbers of rows and columns reach several hundreds to several thousands is required and the uniform device characteristic of each surface conduction electron-emitting device are desired. Many surface conduction electron-emitting devices must be uniformly and rapidly manufactured in order to actually produce various kinds of image-forming panels with high grade and high definition.
For example, as a method for manufacturing plural surface conduction electron-emitting devices by the energization forming, the present applicants have already made an application for the energization method (Japanese Patent Application Laid-open No. 7-176265).
In addition, as a method for manufacturing a plurality of the surface conduction electron-emitting devices by the energization activation operation, the present applicants conducted the method by which the surface conduction electron-emitting devices matrix-wired in procession are divided into multiple groups and a voltage for the energization activation is sequentially applied in group units. That is, for example, the voltage for activation is sequentially applied to the surface conduction electron-emitting devices arranged in M rows and N columns such as shown in FIG. 24 row by row, one row being used as a unit. In the drawing, reference characters EY1 to EYn and EX1 to EXM represent a wiring.
FIG. 25 illustrates a case where a voltage for energization activation is applied to the surface conduction electron-emitting device in, for example, the second row, and a voltage source for energization activation is connected to the wiring in the second row while a ground level, i.e., 0(V) is connected to any other electrode as shown in the drawing. According to this method, the voltage for energization activation is applied only to the surface conduction electron-emitting device in the second row in principle, and no voltage is applied to other surface conduction electron-emitting devices or no electric current is caused to flow thereto. When the energization activation was actually carried out by using this method, the uniformity of the electron-emitting characteristic of the surface conduction electron-emitting devices was improved.
Such a method for applying the voltage for activation can be similarly applied to a multi-surface conduction electron-emitting device substrate having the ladder-like wiring.
An object of the present invention is, in the above-described energization operation method in production of an electron source, to provide novel means and method by which an electron source including a plurality of electron-emitting devices having a uniform characteristic can be manufactured.
Another object of the present invention is, in an energization activation method in the above-mentioned energization operation method in particular, to provide novel means and method by which an electron source including a plurality of electron-emitting devices having a uniform characteristic can be manufactured.
The present invention provides an apparatus for manufacturing an electron source which is disposed on a substrate and has a plurality of electron-emitting devices connected by a wiring, the apparatus for manufacturing an electron source comprising electrical connecting means connected to the wiring at three or more points.
Further, the present invention provides a method for manufacturing an electron source which is disposed on a substrate and has a plurality of electron-emitting devices connected by a wiring, the method for manufacturing an electron source comprising an energization step carried out by energization from the electrical connecting means connected to the wiring at three or more points.
Furthermore, the present invention provides a method for manufacturing an electron source comprising the steps of: forming a plurality of electroconductive films connected by wiring on a substrate; and energizing a plurality of the electroconductive films by the electrical connecting means connected to the wiring at three or more points, a temperature of the substrate being controlled in the energizing step.
Moreover, the present invention provides a method for manufacturing an electron source comprising the steps of: forming a plurality of electroconductive films matrix-wired by a plurality of row-direction wiring and a plurality of column-direction wiring on a substrate; and energizing a plurality of the electroconductive films by the electrical connecting means connected to the row-directional wiring at three or more points, a temperature of the substrate being controlled in the energizing step.
In addition, the present invention provides a method for manufacturing an electron source comprising the steps of: forming a plurality of electroconductive films matrix-wired by a plurality of row-directional wiring and a plurality of column-directional wiring on a substrate; and energizing a plurality of the electroconductive films by the electrical connecting means connected to two or more row-directional wiring of a plurality of the row-directional wiring and respectively connected to the two or more row-directional wiring at three or more points, a temperature of the substrate being controlled in the energizing step.